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181.
Yoichi Haji Makiko Suzuki Kunihiko Moriya Takanori So Katsuto Hozumi Masamichi Mizuma Michiaki Unno Naoto Ishii 《Biochemical and biophysical research communications》2014
Notch1 mutations are found in more than 50% of human T cell acute lymphoblastic leukemia (T-ALL) cells. However, the functions of Notch1 for human T cell development and leukemogenesis are not well understood. To examine the role of Notch1, human hematopoietic stem cells (HSCs), which had been transduced with a constitutively active form of Notch1 (ICN1), were transplanted into severely immunodeficient NOD/Shi-scid-IL2rγnull (NOG) mice. We found that the great majority of the ICN1-expressing hematopoietic cells in the bone marrow expressed surface markers for T cells, such as CD3, CD4, and CD8, and that this T cell development was independent of the thymus. Accordingly, phenotypically mature CD8+ single positive (SP) T cells were observed in the spleen. Furthermore, T-ALL developed in one NOG recipient mouse out of 26 that had been secondary transferred with the T cells developed in the first NOG mice. These results indicate that Notch1 signaling in HSCs promotes CD8+ SP T cell development, and that T cell leukemogenesis may require additional oncogenic factors other than Notch1 activation. 相似文献
182.
Kornsorn Srikulnath Kazumi Matsubara Yoshinobu Uno Chizuko Nishida Mats Olsson Yoichi Matsuda 《Chromosoma》2014,123(6):563-575
The sand lizard (Lacerta agilis, Lacertidae) has a chromosome number of 2n?=?38, with 17 pairs of acrocentric chromosomes, one pair of microchromosomes, a large acrocentric Z chromosome, and a micro-W chromosome. To investigate the process of karyotype evolution in L. agilis, we performed chromosome banding and fluorescent in situ hybridization for gene mapping and constructed a cytogenetic map with 86 functional genes. Chromosome banding revealed that the Z chromosome is the fifth largest chromosome. The cytogenetic map revealed homology of the L. agilis Z chromosome with chicken chromosomes 6 and 9. Comparison of the L. agilis cytogenetic map with those of four Toxicofera species with many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) showed highly conserved linkage homology of L. agilis chromosomes (LAG) 1, 2, 3, 4, 5(Z), 7, 8, 9, and 10 with macrochromosomes and/or macrochromosome segments of the four Toxicofera species. Most of the genes located on the microchromosomes of Toxicofera were localized to LAG6, small acrocentric chromosomes (LAG11–18), and a microchromosome (LAG19) in L. agilis. These results suggest that the L. agilis karyotype resulted from frequent fusions of microchromosomes, which occurred in the ancestral karyotype of Toxicofera and led to the disappearance of microchromosomes and the appearance of many small macrochromosomes. 相似文献
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Eiji Yamamoto Tomonori Takashi Yoichi Morinaka Shaoyang Lin Jianzhong Wu Takashi Matsumoto Hidemi Kitano Makoto Matsuoka Motoyuki Ashikari 《Molecular genetics and genomics : MGG》2010,283(4):305-315
Reproductive isolation plays an important role in speciation as it restricts gene flow and accelerates genetic divergence
between formerly interbreeding population. In rice, hybrid breakdown is a common reproductive isolation observed in both intra
and inter-specific crosses. It is a type of post-zygotic reproductive isolation in which sterility and weakness are manifested
in the F2 and later generations. In this study, the physiological and molecular basis of hybrid breakdown caused by two recessive genes,
hbd2 and hbd3, in a cross between japonica variety, Koshihikari, and indica variety, Habataki, were investigated. Fine mapping of hbd2 resulted in the identification of the causal gene as casein kinase I (CKI1). Further analysis revealed that hbd2-CKI1 allele gains its deleterious function that causes the weakness phenotype by a change of one amino acid. As for the other
gene, hbd3 was mapped to the NBS-LRR gene cluster region. It is the most common class of R-gene that triggers the immune signal in response to pathogen attack. Expression analysis of pathogen response marker genes
suggested that weakness phenotype in this hybrid breakdown can be attributed to an autoimmune response. So far, this is the
first evidence linking autoimmune response to post-zygotic isolation in rice. This finding provides a new insight in understanding
the molecular and evolutionary mechanisms establishing post-zygotic isolation in plants. 相似文献
186.
One of the major objectives of the Human Genome Project is to understand the biological function of the gene and genome as well as to develop clinical applications for human diseases. For this purpose, the experimental validations and preclinical trails by using animal models are indispensable. The mouse (Mus musculus) is one of the best animal models because genetics is well established in the mouse and embryonic manipulation technologies are also well developed. Large-scale mouse mutagenesis projects have been conducted to de-velop various mouse models since 1997. Originally, the phenotype-driven mutagenesis with N-ethyl-N-nitrosourea (ENU) has been the major efforts internationally then knockout/conditional mouse projects and gene-driven mutagenesis have been following. At the beginning, simple monogenic traits in the experimental condition have been elucidated. Then, more complex traits with variety of environmental interactions and gene-to-gene interactions (epistasis) have been challenged with mutant mice. In addition, chromosomal substitution swains and collaborative cross strains are also available to elucidate the complex Waits in the mouse. Altogether, mouse models with mutagenesis and various laboratory strains will accelerate the studies of functional genomics in the mouse as well as in human. 相似文献
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Teruaki Taji Kenji Komatsu Taku Katori Yoshikazu Kawasaki Yoichi Sakata Shigeo Tanaka Masatomo Kobayashi Atsushi Toyoda Motoaki Seki Kazuo Shinozaki 《BMC plant biology》2010,10(1):261
Background
Thellungiella halophila (also known as T. salsuginea) is a model halophyte with a small size, short life cycle, and small genome. Thellungiella genes exhibit a high degree of sequence identity with Arabidopsis genes (90% at the cDNA level). We previously generated a full-length enriched cDNA library of T. halophila from various tissues and from whole plants treated with salinity, chilling, freezing stress, or ABA. We determined the DNA sequences of 20 000 cDNAs at both the 5'- and 3' ends, and identified 9569 distinct genes. 相似文献189.
Shinzato N Watanabe I Meng XY Sekiguchi Y Tamaki H Matsui T Kamagata Y 《Microbial ecology》2007,54(4):627-636
The anaerobic free-living ciliate, Trimyema compressum, is known to harbor both methanogenic archaeal and bacterial symbionts in the cytoplasm. To clarify their phylogenetic belongings,
a full-cycle rRNA approach was applied to this symbiosis. Phylogenetic analysis showed that the methanogenic symbiont was
related to Methanobrevibacter arboriphilicus, which was distantly related to symbionts found in other Trimyema species. This result suggested that Trimyema species do not require very specific methanogenic symbionts, and symbiont replacement could have occurred in the history
of Trimyema species. On the other hand, the bacterial symbiont was located near the lineage of the family Syntrophomonadaceae in the
phylum Firmicutes. The sequence similarity between the bacterial symbiont and the nearest species was 85%, indicating that
bacterial symbionts may be specific to the Trimyema species. The elimination of bacterial symbionts from the ciliate cell by antibiotic treatment resulted in considerably decreased
host growth. However, it was not restored by stigmasterol addition (<2 μg ml−1), which was different from the previous report that showed that the symbiont-free strain required exogenous sterols for growth.
In addition, the decline of host growth was not accompanied by host metabolism shift toward the formation of more reduced
products, which suggested that the contribution of bacterial symbionts to the host ciliate was not a dispose of excessive
reducing equivalent arising from the host’s fermentative metabolism as methanogenic symbionts do. This study showed that bacterial
symbionts make a significant contribution to the host ciliate by an unknown function and suggested that interactions between
bacterial symbionts and T. compressum are more complicated than hitherto proposed. 相似文献
190.